The anisotropy of a three- and a one-form

TL;DR

This paper investigates how a three-form field coupled with a vector gauge field can produce anisotropic signals during inflation, revealing that such couplings likely lead to large anisotropies that challenge their viability.

Contribution

It provides a calculation of anisotropic signals from three-form and vector gauge field couplings, highlighting the potential for exponential amplification of vector fluctuations during inflation.

Findings

Exponential amplification of vector fluctuations in three-form inflation.

Large anisotropies are likely to develop due to this coupling.

Constraints on the viability of three-form inflation models.

Abstract

We calculate the anisotropic signal associated with the coupling of a three-form with an Abelian vector gauge field. In the simplest examples of three-form inflation the amplification of the vector fluctuations is exponential; this makes it almost certain that a large anisotropy will develop, severely constraining the viability of the coupling.